hi chipo, i used to be a pastry chef, so pls pm me if you need any advice.
I agree, kids birthday cakes - indeed any birthday cakes - don't have to look perfect!
Are you planning to stack the cakes on 3 separate cake boards with pillars in between, or all 3 stacked on top of each other? Either way, I don't know if your chiffon cake will hold up to the weight. Ideally madiera cake would be used, simply because it is more dense and "solid", and will take the weight on top of it....I know the cake doesn't need to look pefect, but you don't want it all sinking to one side or something!
If it's for kids, I think the cutest, and really contemporay way to do the cake would be to make individual cupcakes, pipe on some lovely bright pink buttercream, and top each one with the Peppa Pig cupcake toppers available cheaply on Ebay (and, these can also double up as party fovours to send home)
You could display them on a multi-tiered stand made with different sized cake boards and wedding pillars (again, cheap on ebay!)
You could also make your chiffon cake as a small 6 inch-ish size for the top layer, and put the birthday candles/flowers/peppa figuerines on this, and have this layer as the one your child slices.
ps. your cakes look FAB, I could eat some cake now too...well, i could eat cake anytime